Suspicious Explorer Child Process

Identifies a suspicious Windows explorer child process. Explorer.exe can be abused to launch malicious scripts or executables from a trusted parent process.

Rule type: eql

Rule indices:

logs-endpoint.events.*
winlogbeat-*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

Tags:

Elastic
Host
Windows
Threat Detection
Initial Access

Version: 4 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 7.13.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

edit

process where event.type in ("start", "process_started") and (
process.name : ("cscript.exe", "wscript.exe", "powershell.exe",
"rundll32.exe", "cmd.exe", "mshta.exe", "regsvr32.exe") or
process.pe.original_file_name in ("cscript.exe", "wscript.exe",
"PowerShell.EXE", "RUNDLL32.EXE", "Cmd.Exe", "MSHTA.EXE",
"REGSVR32.EXE") ) and /* Explorer started via DCOM */
process.parent.name : "explorer.exe" and process.parent.args :
"-Embedding" and not process.parent.args: ( /*
Noisy CLSID_SeparateSingleProcessExplorerHost Explorer COM Class IDs
*/ "/factory,{5BD95610-9434-43C2-886C-57852CC8A120}",
"/factory,{ceff45ee-c862-41de-aee2-a022c81eda92}" )

Threat mapping

edit

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
Technique:
- Name: Phishing
- ID: T1566
- Reference URL: https://attack.mitre.org/techniques/T1566/

Rule version history

edit

Version 4 (7.13.0 release)

Updated query, changed from:

process where event.type in ("start", "process_started") and
process.name : ("cscript.exe", "wscript.exe", "powershell.exe",
"rundll32.exe", "cmd.exe", "mshta.exe", "regsvr32.exe") and /*
Explorer started via DCOM */ process.parent.name : "explorer.exe"
and process.parent.args : "-Embedding"

Version 3 (7.12.0 release)

Formatting only

Version 2 (7.11.2 release)

Formatting only

« Suspicious Execution via Scheduled Task Suspicious Hidden Child Process of Launchd »